Ultra small spot generator

ABSTRACT

An interferometer is used to provide control to the intensity profile and position of a spot of light. In this invention, each light ray from a spectral source is regenerated into a plurality of light rays by an interferometer. These rays are focused by a lens into a constructive interference fringe on an optical disk. A voltage across the interferometer can change the index of reflection of the interferometer thus defines the position of the constructive interference fringe on the disk.

[0001] This is a continuation in part application of U.S. patent application Ser. No. 09/035,824, filed on Mar. 6, 1998, by Roland H. Chase.

BACKGROUND OF THE INVENTION

[0002] The technological growth of the computer industry has been progressing at an extremely fast pace. Products that are barely three years old are considered obsolete. The demand for more powerful computers translates into demands of faster data processing speed and greater data storage capacity. The present invention fits in the category of meeting the demand for greater data storage capacity. Presently, data stored on an optical data storage device are retrieved by observing the behavior of light being reflected from the optical data storage device. As storage capacity increases, the amount of data per unit of area increases. A practical limitation of the storage capacity of an optical data storage device is the size of a spot of light that can be generated by a reader head. The present invention discloses a spot of light that is many orders of magnitudes smaller than those currently being used in the market place.

SUMMARY OF THE INVENTION

[0003] The present invention discloses a novel method and apparatus to produce an extremely small spot of light.

BRIEF DESCRIPTION OF THE DRAWING

[0004]FIG. 1 illustrates a first embodiment of an optical configuration using a Fabry-Perot interferometer and a spectral light source.

[0005]FIG. 2 illustrates the annular ring constructive interference fringes produced by the first embodiment as shown in FIG. 1.

[0006]FIG. 3 illustrates a second embodiment of the present invention.

[0007]FIG. 4 illustrates the annular ring constructive interference fringes produced by the second embodiment of the present invention as shown in FIG. 3.

[0008]FIG. 5 illustrates a third embodiment of the present invention using two Fabry-Perot interferometers.

[0009]FIG. 6 illustrates two annular ring constructive interference fringes produced by the third embodiment of the present invention as shown in FIG. 5.

[0010]FIG. 7 illustrates a Fabry-Perot interferometer configured as an electro-optical device containing a media inside the interferometer that exhibits Kerr or Pockel effect.

DETAILED DESCRIPTION OF THE INVENTION

[0011]FIG. 1 shows an optical system employing a conventional Fabry-Perot interferometer. The Fabry-Perot interferometer is an angle filter and is the basis of this invention.

[0012] In FIG. 1, the X-axis is parallel to an optical axis, 395, of the objective lens, 300. The Y-axis lies in a plane of the drawing and is perpendicular to axis 395. The Z-axis is perpendicular to the plane of the drawing.

[0013] A spectral light source, 100, emits a pencil of light rays, 190. The central ray, 195, of pencil, 190, is incident on a Fabry-Perot interferometer, 210, normal, 212, to entrance face, 211. Central ray, 195, is parallel to an optical axis, 395, of the Objective lens, 300.

[0014] It is a long established principle of multiple-beam interference phenomenon, well known to those skilled in the art of physical optics, that of the infinite number of rays incident on a Fabry-Perot interferometer only those having unique angles, with respect to the normal, 212, to the entrance face, 211, can successfully be transited through the interferometer. All other rays suffer destructive interference and are filtered out of the pencil.

[0015] Those rays successfully transiting through interferometer 210 are collected by Objective lens, 300, and converged into annular constructive interference fringe rings on a focal plane, 400. These annular constructive interference fringe rings are shown in FIG. 2. Here the central fringe 500 is shown at the focal point of lens 300 with the first annular ring fringe, 510, at a radius r1. Here r1 is defined as:

r 1=arctan(01/f)

[0016] Where 01 is an angle, with respect to normal 212, inside pencil 190 and f is the focal length of lens, 300. Likewise r2 and r3 are defined as:

r 2=arctan(02/f)

[0017] And

r 3=arctan(03/f)

[0018] It should be noted that the closer is the fringe to the focal point of lens 300, the wider is the fringe. Conversely, the farther is a fringe from the focal point, the narrower is the fringe. Since FIG. 2 is drawn on white paper, the colors are reversed. The black rings actually represent high intensity constructive interference fringe rings and the white spacing between represents regions void of light, also known as regions of destructive interference where the light has been filtered out of pencil 190.

[0019] The second embodiment of the present invention is shown in FIG. 3. This is a modification of FIG. 1 wherein interferometer 210 has been rotated an angle 01 about the Z-axis. This causes fringe 510 to be displaced, in focal plane 400, along the Y-axis by a distance r1, as shown in FIG. 4.

[0020] The third embodiment of the present invention is shown in FIG. 5. This is a modification of FIG. 3 wherein a second Fabry-Perot interferometer, 220, has been added. For the sake of clarity, the fringe that would be transmitted by interferometer is labeled as 500 a while those that would be transmitted by interferometer 220 are labeled as 510 b.

[0021] Here interferometer 210 has been rotated an angle 01 about the Y-axis and interferometer 220 has been rotated by an angle 01 about the Z-axis. This causes fringe 510 a to be displaced, in the focal plane of lens 300, along the Y-axis a distance r1 and fringe 510 b to be displaced, in the focal plane of lens 300, along the Z-axis a distance r1, as shown in FIG. 6.

[0022] Because interferometer 210 can only transmit rays making an angle 01 with respect to the normal to its entrance face and interferometer 220 can only transmit rays making an angle 01 with respect to the normal to its entrance face, there are only spots in the focal plane where this condition can be satisfied. The preferred spot is located at the focal point of lens 300. The other spot lies on a diagonal bisecting the Y-axis and Z-axis. The other spot is masked out.

[0023] The Fabry-Perot interferometer is one member of a family of instruments that employ the principle of multiple-beam interference. Other members of this family are the Lummer-Gehreke interferometer, the interference filter, and the frustrated total reflection interference filter. All of these instruments regenerate every single ray, from a pencil of rays, into a multitude of parallel, geometrically degraded amplitude, phase related rays. When each set of parallel rays are brought to separate points in the focal plane of a lens, they will interfere with each other. The intensity of the light at each point is dependent upon optical path difference between sequential parallel rays has traveled. If the path difference between sequential sets of rays is an integer number of wavelengths, then the intensity is at a maximum. If it is a half integer, the intensity is zero. Any other value of the path difference will yield an intermediate intensity.

[0024] Thus, in addition to the Fabry-Perot interferometer, this invention will function with either a Lummer-Gehreke interferometer, an interference filter, or a frustrated total reflection interference filter.

[0025]FIG. 7 illustrates by way of an example a Fabry-Perot interferometer also functioning as an electro-optical device employs the Kerr or Pockel effect. It should be noted that the electro-optical device can also be a Lummer-Gehreke interferometer, interference filter, or frustrated total reflection interference filter. The medium inside the Fabry-Perot interferometer, Lummer-Gehreke interferometer, interference filter, or frustrated total reflection interference filter can be an electro-optical material so that a voltage applied across therein will change the index of the medium thus causing the angles that can propagate through the instrument to change. The medium can be various types of gases, liquids or solids, such as KD*P.

[0026] A design sample showing detailed calculations and designed parameters are included hereinbelow. As shown, the total number of bytes that can be easily generated by the present invention is in the order of 109.1 giga bytes on a 120-millimeter diameter disk.

[0027] If the medium between the reflecting surfaces is an electro-optical material then the optical path changes as the result of an electric, or magnetic field applied across the device. This in turn causes the angle at which constructive interference occurs to change thus producing a change in the position of the spot, or constructive interference fringe.

[0028] A magnetic, or electric field applied to the spectral source will cause the wavelength of the source to change. This also causes the position of the spot to change.

[0029] From the foregoing detailed description, it will be evident that there are a number of changes, adaptations and modifications of the present invention which come within the province of those persons having ordinary skill in the art to which the aforementioned invention pertains. However, it is intended that all such variations not departing from the spirit of the invention be considered as within the scope thereof as limited solely by the appended claims. 

I claim:
 1. A device to produce a high intensity and ultra small spot of light on a focal plane, comprising: means for generating a pencil of light rays; an interferometer; and a lens; wherein the pencil of light rays is transmitted along an X-axis respectively through the interferometer and the lens to become the high intensity and ultra small spot of light upon reaching the focal plane.
 2. The apparatus of claim 1, wherein the interferometer is one of a Fabry-Perot interferometer and a Lummei-Gehrcke interferometer.
 3. The apparatus of claim 2, wherein the Fabry-Perot interferometer is an interference filter.
 4. The apparatus of claim 2, wherein the Fabry-Perot interferometer is a frustrated total reflection interference filter.
 5. The apparatus of claim 2, wherein the Fabry-Perot interferometer is an electro-optical device having an electro-optical Kerr effect.
 6. The apparatus of claim 3, wherein the interference filter is an electro-optical device having an electro-optical Kerr effect.
 7. The apparatus of claim 4, wherein the frustrated total reflection interference filter is an electro-optical device having an electro-optical Kerr effect.
 8. The apparatus of claim 1, wherein the interferometer has a light entrance surface that is perpendicular to the X-axis.
 9. The apparatus of claim 1, wherein the interferometer has a light entrance surface that is rotated about one of a Z-axis and an Y-axis by an angle θ.
 10. A device to produce a high intensity and ultra small spot of light on a focal plane, comprising: means for generating a pencil of light rays; a first interferometer; a second interferometer; and a lens; wherein the pencil of light rays is transmitted along an X-axis respectively through the first interferometer, the second interferometer and the lens to become the high intensity and ultra small spot of light upon reaching the focal plane.
 11. The apparatus of claim 10, wherein the first interferometer is one of a Fabry-Perot interferometer and a Lummer-Gehrcke interferometer.
 12. The apparatus of claim 10, wherein the second interferometer is one of a Fabry-Perot interferometer and a Lummer-Gehrcke interferometer.
 13. The apparatus of claims 11, wherein the Fabry-Perot interferometer is an interference filter.
 14. The apparatus of claim 11, wherein the Fabry-Perot interferometer is a frustrated total reflection interference filter.
 15. The apparatus of claim 10, wherein the Fabry-Perot interferometer is an electro-optical device having an electro-optical Kerr effect.
 16. The apparatus of claim 13, wherein the interference filter is an electro-optical device having an electro-optical Kerr effect.
 17. The apparatus of claim 14, wherein the frustrated total reflection interference filter is an electro-optical device having an electro-optical Kerr effect.
 18. The apparatus of claim 10, wherein the first interferometer has a light entrance surface that is rotated about a Z-axis by an angle α and the second interferometer has a light entrance surface that is rotated about a Y-axis by an angle β.
 19. The apparatus of claim 10, wherein the first interferometer has a light entrance surface that is rotated about a Y-axis by an angle α and the second interferometer has a light entrance surface that is rotated about a Z-axis by an angle β.
 20. A device to produce an ultra small spot of light on a focal plane comprising in combination: a) means for generating a pencil of light rays; b) an interferometer; and c) a lens; wherein said pencil of rays is transmitted through said interferometer and said lens to form a constructive interference fringe on the focal plane of said lens.
 21. The apparatus of claim 20 wherein the means for generating a pencil of light rays is a spectral source.
 22. The apparatus of claim 20 wherein the interferometer is a Fabry-Perot interferometer.
 23. The apparatus of claim 20 wherein the interferometer is a Lummer-Gehrcke interferometer.
 24. The apparatus of claim 20 wherein the interferometer is an interference filter.
 25. The apparatus of claim 20 wherein the interferometer is a frustrated total reflection interference filter.
 26. The apparatus of claim 20 wherein the medium inside said interferometer is an electro-optic material.
 27. The apparatus of claim 22 wherein the medium inside said Fabry-Perot interferometer is an electro-optic material.
 28. The apparatus of claim 23 wherein the medium inside said Lummer-Gehrcke interferometer is an electro-optic material.
 29. The apparatus of claim 24 wherein the medium inside said interference filter is an electro-optic material.
 30. The apparatus of claim 25 wherein the medium inside said frustrated total reflection interference filter is an electro-optic material.
 31. A device to produce an ultra small spot of light comprising in combination: a) means for generating a pencil of light rays; b) a first interferometer for controlling the profile of the said spot in one axis; c) a second interferometer for controlling the profile of the said spot in an orthogonal axis; and a d) lens; wherein said pencil of rays is transmitted through said first interferometer, said second interferometer, and said lens to form a constructive interference fringe on the focal plane of said lens.
 32. The apparatus of claim 31 wherein the means for generating a pencil of light rays is a spectral source.
 33. The apparatus of claim 31 wherein either or both said interferometers are Fabry-Perot interferometers.
 34. The apparatus of claim 31 wherein either or both said interferometers are Lummer-Gehrcke interferometers.
 35. The apparatus of claim 31 wherein either or both said interferometers are interference filters.
 36. The apparatus of claim 31 wherein either or both said interferometers are frustrated total reflection interference filters.
 37. The apparatus of claim 31 wherein the medium inside either or both said interferometers is an electro-optic material.
 38. The apparatus of claim 33 wherein the medium inside either or both said Fabry-Perot interferometers is an electro-optic material.
 39. The apparatus of claim 33 wherein the medium inside either or both said Lummer-Gehrcke interferometers is an electro-optic material.
 40. The apparatus of claim 33 wherein the medium inside either or both said interference filters is an electro-optic material.
 41. The apparatus of claim 34 wherein the medium inside either or both said frustrated total reflection interference filters is an electro-optic material.
 43. A device to produce an ultra-small spot of light whose position in a plane can be controlled by an electric field comprising in combination a: a) means for generating a pencil of light rays; a e) first interferometer for controlling the position of the said spot in one axis; a f) second interferometer for controlling the position of the said spot in an orthogonal axis; and a g) lens; wherein the magnetic field is produced inside the said means for generating said pencil of light rays; wherein the electro-optic quarter-wave plate renders tile circularly polarized light linearly polarized; wherein the polarizing filter eliminates one of the two wavelengths; wherein the central ray of the said pencil of rays is coincident with the optical axis of said lens; wherein the normal to the entrance face of the said first Fabry-Perot interferometer is set at an angle to the optical axis of the said lens; wherein the normal to the entrance face of the said second Fabry-Perot interferometer is set at an angle to the optical axis of the said lens; wherein the plane formed by the said optical axis and the normal to the entrance face of the said first Fabry-Perot interferometer and the plane formed by the said optical axis and the normal to the entrance face of the said second Fabry-Perot interferometer are orthogonal; wherein the said pencil of light rays is smaller than the aperture of the said lens.
 44. A device to produce an ultra small spot of light whose position in a plane can be controlled by a magnetic field comprising in combination: a) means for generating a pencil of light rays; b) a magnetic field; c) an electro-optic quarter-wave plate; d) a polarizing filter; e) a first interferometer for controlling the profile of the said spot in one axis; f) a second interferometer for controlling the profile of the said spot in an orthogonal axis; and g) a lens; wherein the magnetic field is produced inside the said means for generating said pencil of light rays; wherein the electro-optic quarter-wave plate renders the circuitry polarized light linearly polarized; wherein the polarizing filter eliminates one of the two wavelengths; wherein the central ray of the said pencil of rays is coincident with the optical axis of the said lens; wherein the normal to the entrance face of the said first Fabry-Perot interferometer is set at alt angle to the optical axis of the said lens; wherein the normal to the entrance face of the said second Fabry-Perot interferometer is set at an angle to the optical axis of the said lens; wherein the plane formed by the said optical axis and the normal to the entrance face of the said first Fabry-Perot interferometer and the plane formed by the said optical axis and the normal to the entrance face of the said second Fabry-Perot interferometer are orthogonal; wherein the said pencil of light rays is smaller than the aperture of the said lens.
 45. A device to produce an ultra small spot of light on a focal plane comprising in combination: a) means for generating a pencil of light rays; b) an interferometer; and c) a lens; wherein said pencil of rays is transmitted through said interferometer and said lens to form a constructive interference fringe on the focal plane of said lens.
 46. The apparatus of claim 45 wherein the means for generating a pencil of light rays is a spectral source.
 47. The apparatus of claim 45 wherein the interferometer is a Fabry-Perot interferometer.
 48. The apparatus of claim 45 wherein the interferometer is a Lummer-Gehrcke interferometer.
 49. The apparatus of claim 45 wherein the interferometer is an interference filter.
 50. The apparatus of claim 45 wherein the interferometer is a frustrated total reflection interference filter.
 51. The apparatus of claim 45 wherein the interferometer is an electro-optical device containing a medium inside said interferometer that exhibits the Kerr or Pockel effect.
 52. The apparatus of claim 47 wherein said Fabry-Perot interferometer is an electro-optical device containing a medium inside said interferometer that exhibits the Kerr or Pockel effect.
 53. The apparatus of claim 48 wherein the said Lummer-Gehrcke interferometer is an electro-optical device containing a medium inside said interferometer that exhibits the Kerr or Pockel effect.
 54. The apparatus of claim 49 wherein the said interference filter is an electro-optical device containing a medium inside said interference filter that exhibits the Kerr or Pockel effect.
 55. The apparatus of claim 50 wherein said frustrated total reflection interference filter is an electro-optical device containing a medium inside said frustrated total reflection interference filter that exhibits the Kerr or Pockel effect.
 56. A device to produce an ultra small spot of light comprising in combination: a) means for generating a pencil of light rays; b) a first interferometer for controlling the profile of the said spot in one axis; c) a second interferometer for controlling the profile of the said spot in an orthogonal axis; and d) a lens; wherein said pencil of rays is transmitted through said first interferometer, said second interferometer, and said lens to form a constructive interference fringe on the focal plane of said lens.
 57. The apparatus of claim 56 wherein the means for generating a pencil of light rays is a spectral source.
 58. The apparatus of claim 56 wherein either or both said interferometers are Fabry-Perot interferometers.
 59. The apparatus of claim 56 wherein either or both said interferometers are Lummer-Gehrcke interferometers.
 60. The apparatus of claim 56 wherein either or both said interferometers are interference filters.
 61. The apparatus of claim 56 wherein either or both said interferometers are frustrated total reflection interference filters.
 62. The apparatus of claim 56 wherein either or both said interferometers are electro-optical devices containing media inside said interferometers that exhibit the Kerr or Pockel effect.
 63. The apparatus of claim 58 wherein either or both said Fabry-Perot interferometers are electro-optical devices containing media inside either or both said Fabry-Perot interferometers that exhibit the Kerr or Pockel effect.
 64. The apparatus of claim 58 wherein either or both said Lummer-Gehrcke interferometers are electro-optical devices containing media inside either or both said Lummer-Gehrcke interferometers that exhibit the Kerr or Pockel effect.
 65. The apparatus of claim 58 wherein either or both said interference filters are electro-optical devices containing media inside either or both said interference filters that exhibit the Kerr or Pockel effect.
 66. The apparatus of claim 59 wherein either or both said frustrated total reflection interference filters are electro-optical devices containing media inside either or both said frustrated total reflection interference filters that exhibit the Kerr or Pockel effect.
 67. A device to produce an ultra small spot of light whose position in a plane can be controlled by an electric field comprising in combination: a) means for generating a pencil of light rays; b) a first Fabry-Perot interferometer for controlling the position of the said spot in one axis; c) a second Fabry-Perot interferometer for controlling the position of the said spot in an orthogonal axis; and d) a lens; wherein the central ray of said pencil of rays is parallel to the optical axis of said lens; wherein the normal to the entrance face of said first Fabry-Perot interferometer is set at an angle to the optical axis of said lens; wherein the normal to the entrance face of said second Fabry-Perot interferometer is set at an angle to the optical axis of said lens; wherein the plane formed by said optical axis and the normal to the entrance face of said first Fabry-Perot interferometer and the plane formed by said optical axis and the normal to the entrance face of said second Fabry-Perot interferometer are orthogonal; wherein said pencil of light rays is smaller than the aperture of said lens.
 68. A device to produce an ultra small spot of light whose position in a plane can be controlled by a magnetic field comprising in combination: a) means for generating a pencil of light rays; b) a magnetic field; c) an electro-optic quarter-wave plate; d) a polarizing filter; e) a first interferometer for controlling the profile of the said spot in one axis; f) a second interferometer for controlling the profile of the said spot in an orthogonal axis; and g) a lens; wherein a magnetic field is produced inside said means for generating said pencil of light rays; wherein said pencil of light rays exhibit multiple wavelengths; wherein said multiple wavelengths are both right and left circularly polarized; wherein the electro-optic quarter-wave plate renders the circularly polarized light linearly polarized; wherein the polarizing filter eliminates one of the two wavelengths; wherein the central ray of the said pencil of rays is parallel to the optical axis of the said lens; wherein the normal to the entrance face of said first Fabry-Perot interferometer is set at an angle to the optical axis of said lens; wherein the normal to the entrance face of said second Fabry-Perot interferometer is set at an angle to the optical axis of said lens; wherein the plane formed by said optical axis and the normal to the entrance face of said first Fabry-Perot interferometer and the plane formed by the said optical axis and the normal to the entrance face of said second Fabry-Perot interferometer are orthogonal; wherein said pencil of light rays is smaller than the aperture of said lens.
 69. The apparatus of claims 12, wherein the Fabry-Perot interferometer is an interference filter.
 70. The apparatus of claim 12, wherein the Fabry-Perot interferometer is a frustrated total reflection interference filter. 